The present invention relates to a light emission device, and in particular, to a light emission device that is efficient and is used for a camera and a camera equipped with the light emission device.
In the case where luminance of an object is low when the object is photographed by a camera, it is conducted that a light emission device is interlocked with shutter releasing to emit light and an appropriate exposure is obtained by reflected light from the object. The light emission device of this type can emit flash light when high voltage is impressed on a light emission tube such as a xenon tube. To utilize effectively light emitted from the light emission tube, there is provided, around the light emission tube, a reflection shade that is left open in one direction.
Incidentally, light emitted from the light emission device is attenuated in accordance with its distance, and it is necessary to emit light of higher intensity in terms of quantity of light for an object located at a greater distance. However, when a light emission device is equipped on a camera, its size and cost are restricted, and it is not always possible to prepare a highly efficient light emission device. Though high voltage is needed for making a xenon tube to emit light, even when a light emission tube is changed to one having a large capacity, there is feared a problem that charging takes a long time, because a capacity of a battery is restricted.
Though a light emission tube is usually arranged in the vicinity of a reflection shade, how to support the light emission tube stably without sacrificing easy assembling while keeping low cost is a problem.
The invention has been achieved in view of the problems stated above, and its object is to provide a light emission device wherein an amount of light emission can be increased only by changing a shape of a reflection shade in a conventional light emission device and a light emission tube can be supported firmly and to provide a camera equipped with the light emission device.
The objects mentioned above are attained by any one of the following structures of light emission devices.
Structure 1: A light emission device having therein a light emission tube which is almost straight in shape and emits light in a radial manner and a reflection shade that reflects light emitted from the light emission tube toward an object, wherein the reflection shade has a reflection surface wherein light emitted from the light emission tube in the direction opposite to the direction from the center of the light emission tube to an object and is reflected on the reflection shade does not interfere with the light emission tube.
Structure 2: A light emission device having therein a light emission tube which is almost straight in shape and emits light in a radial manner and a reflection shade that reflects light emitted from the light emission tube toward an object, wherein the reflection shade has a reflection surface by which a part of reflected light which is to interfere with the light emission tube when the reflected light is reflected on a flat reflection plate that is in contact with the light emission tube is reflected toward the object without interfering with the light emission tube.
Structure 3: A light emission device having therein a light emission tube which is almost straight in shape and emits light in a radial manner and a reflection shade that reflects light emitted from the light emission tube toward an object, wherein the reflection shade has a reflection surface which is behind the position of the reflection shade corresponding to at least the rearmost portion of the light emission tube.
Structure 4: A light emission device having therein a light emission tube which is almost straight in shape and emits light in a radial manner and a reflection shade that reflects light emitted from the light emission tube toward an object, wherein the reflection shade has thereon a ridge which is protruded toward the light emission tube and is extended to be in parallel with the longitudinal direction of the light emission tube.
Structure 5: A light emission device having therein a light emission tube which is almost straight in shape and emits light in a radial manner and a reflection shade that reflects light emitted from the light emission tube toward an object, wherein the reflection shade has thereon a surface that is circumscribed with the rearmost portion of the light emission tube on the inner surface of the reflection shade.
Structure 6: A light emission device having therein a light emission tube which is almost straight in shape and emits light in a radial manner and a reflection shade that reflects light emitted from the light emission tube toward an object, wherein the reflection shade has thereon a groove that is extended to be in parallel with the longitudinal direction of the light emission tube on the side opposite to an object.
Structure 7: A light emission device having therein a light emission tube which is almost straight in shape and emits light in a radial manner and a reflection shade that reflects light emitted from the light emission tube toward an object, wherein the reflection shade has thereon at least two surfaces extended in the direction toward an object and at least two surfaces extended in the direction different from that toward an object, both facing each other with the light emission tube between them.
Structure 8: A light emission device having therein a reflection shade that supports at least a part of a light emission tube which is almost straight in shape and emits light in a radial manner, wherein the reflection shade is equipped with a reflection portion arranged on the circumference of the light emission tube, a flank portion provided on a side edge on at least one side of the reflection portion, and with paired arm portions formed on the flank portion, and the light emission tube is supported between the paired arms, while, the paired arms are formed to keep the form even when the reflection portion is changed in terms of shape in the direction to be opened in the flank portion.
Incidentally, in each Structure, light is made to advance toward an object without advancing toward the light emission tube, which implicates that light subjected to secondary reflection on the reflection surface advances toward an object as a result.
Since a light emission device of Structure 1 is represented by one having therein a light emission tube which is almost straight in shape and emits light in a radial manner and a reflection shade that reflects light emitted from the light emission tube toward an object, wherein the reflection shade has a reflection surface wherein light emitted from the light emission tube in the direction opposite to the direction from the center of the light emission tube to an object and is reflected on the reflection shade does not interfere with the light emission tube, it is possible to reflect light that interferes with the light emission tube and was not utilized effectively in a light emission device in conventional technology, for example, and thereby to increase an amount of emitted light in the light emission device without increasing energy to be inputted in the light emission tube.
Since a light emission device of Structure 2 is represented by one having therein a light emission tube which is almost straight in shape and emits light in a radial manner and a reflection shade that reflects light emitted from the light emission tube toward an object, wherein the reflection shade has a reflection surface by which a part of reflected light which is to interfere with the light emission tube when the reflected light is reflected on a flat reflection plate that is in contact with the light emission tube is reflected toward the object without interfering with the light emission tube, it is possible to reflect light that interferes with the light emission tube and was not utilized effectively in a light emission device in conventional technology, for example, and thereby to increase an amount of emitted light in the light emission device without increasing energy to be inputted in the light emission tube.
Under the conditions that a reflection mirror is in contact with a light emission tube and light is emitted in one direction, when the reflection mirror is a flat reflection mirror, it has been confirmed that light emitted from the light emission tube and reflected on the reflection mirror interferes least with the light emission tube. In other words, in the case of a conventional concave mirror that surrounds a light emission tube, an amount of light interfering with the light emission tube is more than that in the case where a flat reflection mirror (plane mirror) is used.
Each of FIGS. 6-10 is a side view showing positional relationship between light emission tube 21 and plane mirror 22xe2x80x2. As is apparent geometrically from FIGS. 6-8, when the light emission tube 21 is divided roughly by plane P passing the center of the light emission tube 21 and a point where the light emission tube 21 is in contact with plane mirror 22xe2x80x2, light emitted from the range of an angle 0xc2x0-20xc2x0 formed by plane P on the side of plane mirror 22xe2x80x2 on the roughly halved light emission tube 21 interferes with the light emission tube 21 to be unable to advance toward an object.
However, if the plane mirror 22xe2x80x2 is inclined to face upward as shown in FIG. 9, light emitted from light emission tube 21 at the position of angle 20xc2x0 formed with plane P is reflected by plane mirror 22xe2x80x2 and can advance to an object at an emission angle 56xc2x0, for example, without interfering with light emission tube 21. On the other hand, if the plane mirror 22xe2x80x2 is inclined to face downward as shown in FIG. 10, light emitted from light emission tube 21 at the position of angle 20xc2x0 in the same way is reflected by plane mirror 22xe2x80x2 and can advance to an object at an emission angle 42xc2x0, for example, without interfering with light emission tube 21. The invention is one employing this principle. By changing an inclination of plane mirror 22xe2x80x2 in accordance with an angle formed with plane P ideally, it is possible to obtain a continued curved surface which can avoid most the interference of light of a reflection tube.
From the foregoing, it can be said that it is possible to make light to advance toward an object more conspicuously, compared with conventional technologies, if a part of reflected light to interfere with the light emission tube when reflected on the plane reflection plate is represented by reflection light to be reflected within a range of at least 20xc2x0 or more from the point where the light emission tube is in contact with the reflection plate with the light emission tube with the center of the light emission tube serving as an axis, on at least one side of the roughly halved light emission tube when the light emission tube is divided roughly by a plane passing the center of the light emission tube and a point where the light emission tube is in contact with reflection plate.
Incidentally, it is preferable that the reflection shade has thereon a reflection surface on which light emitted from the center of the light emission tube within a range of 100xc2x0 or more in the direction opposite to the direction toward object is reflected without interfering the light emission tube.
Further, it is preferable if light interfering with the light emission tube among light emitted from the light emission tube and reflected on the reflection shade is represented by light emitted from the light emission tube within a range of 40xc2x0 or less.
Since a light emission device of Structure 3 is represented by one having therein a light emission tube which is almost straight in shape and emits light in a radial manner and a reflection shade that reflects light emitted from the light emission tube toward an object, wherein the reflection shade has a reflection surface which is behind the position of the reflection shade corresponding to at least the rearmost portion of the light emission tube, it is possible to reflect light that interferes with the light emission tube and was not utilized effectively in a light emission device in conventional technology, for example, and thereby to increase an amount of emitted light in the light emission device without increasing energy to be inputted in the light emission tube.
Incidentally, it is preferable that the rearmost portion of the light emission tube is its end portion located to be opposite to an object, to which, however, the invention is not limited.
Further, it is preferable that a reflection surface behind the position of the reflection shade corresponding to at least the rearmost portion of the light emission tube has a shape to be isolated from the rearmost portion of the light emission tube, to which, however, the invention is not limited. FIG. 11 is a diagram showing an example of a light emission device having therein light emission tube 21 having rearmost portion 21c and reflection shade 22, satisfying the requirements of the invention, in which, however, the invention is not limited to the structure illustrated in the diagram.
In an example in FIG. 11, reflection shade 22 narrows gradually as its position goes backward beyond light emission tube 21, and it has at least two grooves 22m and 22n extended in the longitudinal direction of the light emission tube 21.
Since a light emission device of Structure 4 is represented by one having therein a light emission tube which is almost straight in shape and emits light in a radial manner and a reflection shade that reflects light emitted from the light emission tube toward an object, wherein the reflection shade has thereon a ridge which is protruded toward the light emission tube and is extended to be in parallel with the longitudinal direction of the light emission tube, it is possible to reflect, by means of the surface of the ridge, light that interferes with the light emission tube and was not utilized effectively in a light emission device in conventional technology, for example, and thereby to increase an amount of emitted light in the light emission device without increasing energy to be inputted in the light emission tube. Incidentally, in the example shown in FIG. 11, the ridge is represented by a portion shown with symbol 22k, to which, however, the invention is not limited.
Further, it is preferable that the light emission tube is in contact with the ridge of the reflection shade.
Since a light emission device of Structure 5 is represented by one having therein a light emission tube which is almost straight in shape and emits light in a radial manner and a reflection shade that reflects light emitted from the light emission tube toward an object, wherein the reflection shade has thereon a surface that is circumscribed with the rearmost portion of the light emission tube on the inner surface of the reflection shade, it is possible to reflect light that interferes with the light emission tube and was not utilized effectively in a light emission device in conventional technology, for example, and thereby to increase an amount of emitted light in the light emission device without increasing energy to be inputted in the light emission tube.
Since a light emission device of Structure 6 is represented by one having therein a light emission tube which is almost straight in shape and emits light in a radial manner and a reflection shade that reflects light emitted from the light emission tube toward an object, wherein the reflection shade has thereon a groove that is extended to be in parallel with the longitudinal direction of the light emission tube on the side opposite to an object, it is possible to reflect, by means of the surface of the groove, light that interferes with the light emission tube and was not utilized effectively in a light emission device in conventional technology, for example, and thereby to increase an amount of emitted light in the light emission device without increasing energy to be inputted in the light emission tube. FIG. 12 is a diagram showing an example of a light emission device having therein light emission tube 21 and reflection shade 22 having groove 22r both satisfying requirements of the invention, in which, however, the invention is not limited to the illustrated structure.
In the light emission device that is symmetrical about plane P passing through the center of light emission tube 21 and extending in the direction to halve roughly an opening angle of reflection shade 22 as shown in FIG. 12, it is preferable that light emitted from light emission tube 21 and reflected on reflection surface 22p on the groove positioned on one side of the roughly halved reflection shade 22 is reflected on reflection surface 22q of the reflection shade positioned on the other side of the roughly halved reflection shade, to be radiated toward an object.
Since a light emission device of Structure 7 is represented by one having therein a light emission tube which is almost straight in shape and emits light in a radial manner and a reflection shade that reflects light emitted from the light emission tube toward an object, wherein the reflection shade has thereon at least two surfaces (surfaces 22s and 22t in the example in FIG. 12 to which the invention is not limited) which interpose the light emission tube and extend toward the object and at least two surfaces (surfaces 22p and 22q in the example in FIG. 12 to which the invention is not limited) extending in the direction different from the direction toward the object, it is possible to reflect light that interferes with the light emission tube and was not utilized effectively in a light emission device in conventional technology, for example, and thereby to increase an amount of emitted light in the light emission device without increasing energy to be inputted in the light emission tube.
Since a light emission device of Structure 8 is represented by one having therein a reflection shade that supports at least a part of a light emission tube which is almost straight in shape and emits light in a radial manner, wherein the reflection shade is equipped with a reflection portion arranged on the circumference of the light emission tube, a side portion provided on the side edge on at least one side of the reflection portion and paired arm portions formed on the side portion, and the light emission tube is supported between the paired arm portions, while, the paired arm portions are formed to maintain their shapes even when the reflection portion is deformed in the direction to open in the side portion, it is possible to maintain a relative distance of the arm portions and thereby to support the light emission tube firmly, even when the reflection portion is deformed in the course of incorporating or deformed by a vibration.
Further, it is preferable that the reflection portion is curved to be concaved, the side portion on at least one side is formed with two plate members extending in the direction to face each other from the side of the reflection portion, and the arm portion is formed on one of the two plate members.
Further, when the arm portion has a shape wherein a distance between the arms decreases as it approaches the inner part of the reflection portion, the light emission tube can stably be supported if the light emission tube is urged toward the inner part of the reflection portion by rubber or a spring.
It is preferable that the light emission device is provided in a camera which includes, in this case, a camera of a silver halide type, an electronic camera and a lens-fitted film unit.